- API 감사 로거 추가 - APITesterAuditLogger 클래스 생성

- 회원가입 링크 수정 - href 속성 추가
- Testbed UI 스타일 추가 - CSS/SASS 코드 업데이트

src/main/resources/static/css/main.css

@@ -10815,6 +10815,124 @@ body.index-page-body {
   display: flex;
 }
 
+#testbed-tab {
+  gap: 0;
+}
+#testbed-tab #swagger-ui .info {
+  margin: 24px 0;
+}
+
+.testbed-app-panel {
+  margin: 8px 0 0;
+  padding: 24px;
+  background: #FFFFFF;
+  border: 1px solid #E2E8F0;
+  border-radius: 12px;
+  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
+}
+.testbed-app-panel .testbed-app-panel__head {
+  display: flex;
+  align-items: baseline;
+  flex-wrap: wrap;
+  gap: 4px 8px;
+  margin-bottom: 16px;
+}
+.testbed-app-panel .testbed-app-panel__title {
+  position: relative;
+  padding-left: 16px;
+  font-size: 16px;
+  font-weight: 700;
+  color: #1A1A2E;
+  letter-spacing: -0.01em;
+}
+.testbed-app-panel .testbed-app-panel__title::before {
+  content: "";
+  position: absolute;
+  left: 0;
+  top: 50%;
+  transform: translateY(-50%);
+  width: 4px;
+  height: 15px;
+  background: #0049b4;
+  border-radius: 2px;
+}
+.testbed-app-panel .testbed-app-panel__desc {
+  font-size: 14px;
+  color: #64748B;
+}
+.testbed-app-panel .testbed-app-field {
+  position: relative;
+  max-width: 380px;
+}
+.testbed-app-panel .testbed-app-field::after {
+  content: "";
+  position: absolute;
+  right: 16px;
+  top: 50%;
+  width: 9px;
+  height: 9px;
+  margin-top: -6px;
+  border-right: 2px solid #64748B;
+  border-bottom: 2px solid #64748B;
+  transform: rotate(45deg);
+  pointer-events: none;
+}
+.testbed-app-panel #apps {
+  width: 100%;
+  height: 46px;
+  padding: 0 42px 0 16px;
+  font-family: "Spoqa Han Sans Neo", "SpoqaHanSans", "Noto Sans KR", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
+  font-size: 14px;
+  color: #1A1A2E;
+  background: #F8FAFC;
+  border: 1px solid #E2E8F0;
+  border-radius: 8px;
+  appearance: none;
+  -webkit-appearance: none;
+  -moz-appearance: none;
+  cursor: pointer;
+  transition: all 0.15s ease;
+}
+.testbed-app-panel #apps:hover:not(:disabled) {
+  border-color: #94A3B8;
+  background: #FFFFFF;
+}
+.testbed-app-panel #apps:focus {
+  outline: none;
+  background: #FFFFFF;
+  border-color: #0049b4;
+  box-shadow: 0 0 0 3px rgba(0, 73, 180, 0.14);
+}
+.testbed-app-panel #apps:disabled {
+  color: #94A3B8;
+  background: #F8FAFC;
+  cursor: not-allowed;
+}
+.testbed-app-panel .testbed-app-notice {
+  margin: 16px 0 0;
+  padding: 11px 16px;
+  font-size: 14px;
+  line-height: 1.6;
+  color: #64748B;
+  background: #EFF6FF;
+  border: 1px solid rgba(0, 73, 180, 0.18);
+  border-left: 3px solid #0049b4;
+  border-radius: 6px;
+}
+.testbed-app-panel .testbed-app-notice::before {
+  content: "ⓘ ";
+  color: #0049b4;
+  font-weight: 700;
+}
+@media (max-width: 768px) {
+  .testbed-app-panel {
+    padding: 16px;
+  }
+  .testbed-app-panel .testbed-app-field {
+    max-width: 100%;
+  }
+}
+
 .api-overview-card {
   background: transparent;
   border-radius: 0;

src/main/resources/static/sass/pages/_api-market.scss

@@ -697,6 +697,139 @@
   }
 }
 
+// Testbed 탭: 앱 선택 패널과 Swagger UI 사이 여백 제거
+#testbed-tab {
+  gap: 0;
+
+  #swagger-ui .info {
+    margin: $spacing-lg 0;
+  }
+}
+
+// Testbed 앱 선택 패널 (DJPGPT0001)
+.testbed-app-panel {
+  margin: $spacing-sm 0 0;
+  padding: $spacing-lg;
+  background: $white;
+  border: 1px solid $border-gray;
+  border-radius: $border-radius-lg;
+  box-shadow: $shadow-sm;
+
+  .testbed-app-panel__head {
+    display: flex;
+    align-items: baseline;
+    flex-wrap: wrap;
+    gap: $spacing-xs $spacing-sm;
+    margin-bottom: $spacing-md;
+  }
+
+  .testbed-app-panel__title {
+    position: relative;
+    padding-left: $spacing-md;
+    font-size: $font-size-base;
+    font-weight: $font-weight-bold;
+    color: $text-dark;
+    letter-spacing: -0.01em;
+
+    &::before {
+      content: "";
+      position: absolute;
+      left: 0;
+      top: 50%;
+      transform: translateY(-50%);
+      width: 4px;
+      height: 15px;
+      background: $primary-blue;
+      border-radius: 2px;
+    }
+  }
+
+  .testbed-app-panel__desc {
+    font-size: $font-size-sm;
+    color: $text-gray;
+  }
+
+  .testbed-app-field {
+    position: relative;
+    max-width: 380px;
+
+    &::after {
+      content: "";
+      position: absolute;
+      right: $spacing-md;
+      top: 50%;
+      width: 9px;
+      height: 9px;
+      margin-top: -6px;
+      border-right: 2px solid $text-gray;
+      border-bottom: 2px solid $text-gray;
+      transform: rotate(45deg);
+      pointer-events: none;
+    }
+  }
+
+  #apps {
+    width: 100%;
+    height: 46px;
+    padding: 0 42px 0 $input-padding-x;
+    font-family: $font-family-primary;
+    font-size: $font-size-sm;
+    color: $text-dark;
+    background: $gray-bg;
+    border: 1px solid $border-gray;
+    border-radius: $border-radius-md;
+    appearance: none;
+    -webkit-appearance: none;
+    -moz-appearance: none;
+    cursor: pointer;
+    transition: $transition-fast;
+
+    &:hover:not(:disabled) {
+      border-color: $text-light;
+      background: $white;
+    }
+
+    &:focus {
+      outline: none;
+      background: $white;
+      border-color: $primary-blue;
+      box-shadow: 0 0 0 3px rgba($primary-blue, 0.14);
+    }
+
+    &:disabled {
+      color: $text-light;
+      background: $gray-bg;
+      cursor: not-allowed;
+    }
+  }
+
+  .testbed-app-notice {
+    margin: $spacing-md 0 0;
+    padding: 11px $spacing-md;
+    font-size: $font-size-sm;
+    line-height: $line-height-normal;
+    color: $text-gray;
+    background: $light-bg;
+    border: 1px solid rgba($primary-blue, 0.18);
+    border-left: 3px solid $primary-blue;
+    border-radius: $border-radius-sm;
+
+    &::before {
+      content: "ⓘ ";
+      color: $primary-blue;
+      font-weight: $font-weight-bold;
+    }
+  }
+
+  @media (max-width: $breakpoint-sm) {
+    padding: $spacing-md;
+
+    .testbed-app-field {
+      max-width: 100%;
+    }
+  }
+}
+
 // API Overview Card (Flat Style)
 .api-overview-card {
   background: transparent;

src/main/resources/templates/views/fragment/djbank/header_container.html

@@ -71,7 +71,7 @@
 
             <div class="auth-group" sec:authorize="isAnonymous()">
               <a th:href="@{/login}" class="login-btn login-btn-box">로그인</a>
-              <a href="#" class="btn-signup">회원가입</a>
+              <a th:href="@{/signup}" class="btn-signup">회원가입</a>
             </div>
 
             <!-- Logout State (Authenticated) -->